They're separate programs and system services which all more or less just do their own thing, just developed under the systemd umbrella. So it can't be "toggled", you can just not use the parts of systemd you don't want.

But it's meant to work as a cohesive system when everything in systemd is used together.

FWIW, I think it's great that someone is trying to make a coherent set of system services for Linux. Things tend to interoperate better when they're explicitly written to work together than when every component is meant to be hacked to work with arbitrary other services through shell script soup.

It's great that the same someone has formed a company called Amutable which has the sole purpose of converting Linux to a locked-down immutable OS where the users doesn't have the key.

Also it's interesting that a set of simple interfaces have worked for so long. Maybe they did something wrong that it didn't break?

See: https://www.amutable.com

> converting Linux to a locked-down immutable OS

That approach is part of why Valve has been able to ship Linux to general consumers.

I don't know exactly why you'd go for amutable specifically, but not handing users the key is a huge benefit to any company-owned hardware out there.

Having an immutable OS for some scenarios makes sense. However, I find waving the whole layer into systemd and kernel permanently, instead of having it as a layer which you can install and enable if you need so is a bit sinister.

This enables the danger of locking out every Linux distribution out there, esp. with new IPC protocols, new image based installation methods, encryption and whatnot systemd brings in with all these modules.

One day, Microsoft can disallow disabling of secure-boot for PC certification and stop signing 3rd party bootloaders. The rest will be fun.

> instead of having it as a layer which you can install and enable if you need so is a bit sinister

I don't really get it. If you don't want systemd, you can install your own OpenRC-based immutable OS. I don't know if that currently exists (Android does, I suppose? maybe ChromeOS?) but it's not like systemd is forbidding everyone from doing anything.

The biggest difference between systemd and alternatives is that systemd builds out the architecture that makes things like building immutable distros easy. If you have a thousand different components, all with slightly different roles, the amount of coordination necessary to get everything to play nice together makes it near impossible to achieve the same things a coordinated system can achieve.

I'm sure that if someone would build an alternative to systemd-sysext and prepare a prebuilt set of tooling and configuration that does what systemd does, there will be distros that will use them.

Secure boot can be overridden by just adding your own keys. At worst, Microsoft will refuse to boot Windows because you added a key yourself. The exception is extra expensive, specially labeled Enterprime (TM) hardware built for Windows sysadmins and Microsoft tablets built for consumers, but I don't know why you'd buy either if you don't want to give MS that much control.

Lennart Poettering will not rest until all software is completely unusable.

Right, are any of the things mentioned in the GP really required if you only want this init?

I know they've attached all these projects to the systemd brand because they thought it would beneficial but it's hard not to wonder if we could avoid all those discussions if the umbrella project was called something different...

No, you can just run the systemd init system and not use any other systemd programs.

I would probably run systemd-journald just because it's really nice to have a logging system which knows about the system services, but it's not required.

You probably also want to run udev, and logind comes close. Everything other than these four is absolutely optional.